Laptop use on generator power question

Something else you are not seeing on those scope shots is the signal dancing around because it is not a continuous 60hz (making it non-sinusoidal). A single cylinder generator will fire (thrust) at say 0 degrees. It has to pass through 720 degrees before it fires again, slowing down as it does. You can't install enough flywheel to stop this. Most twins do not fire 360 out of phase to assist with this.

Connect an oscilloscope to any internal combustion driven generator (properly isolated of course) using manual trigger and you will see what I'm talking about.

In short, no generator you would buy outputs a pure sine wave.